8
AIR FOR COMBUSTION AND VENTILATION Cont.
1.
Determine the volume of the space (length x width x height).
Length x Width x Height = ______________ cu. ft. (volume of space)
Example:
Space size 22ft. (length) x 18 ft. (width) x 8 ft. (ceiling height) = 3168 cu. ft. (volume of space)
If additional ventilation to adjoining room is supplied with grills or openings, add the volume of these rooms to the total
volume of the space.
2.
Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space can support.
______________ (volume of space)
÷
50 cu. ft. = 63.3 or 63,300 (maximum Btu/Hr the space can support)
3.
Add the Btu/Hr of all fuel burning appliances in the space.
Vent-free logset
__________________ Btu/Hr
Gas water heater*
__________________ Btu/Hr
Gas furnace
__________________ Btu/Hr
Vented gas heater
__________________ Btu/Hr
Gas firebox logs
__________________ Btu/Hr
Other gas appliances*
+ __________________ Btu/Hr
Total
= __________________ Btu/Hr
Example:
Gas water heater
40,000 Btu/Hr
Vent-free firebox with log heater
+ 39,000 Btu/Hr
Total
= 79,000Btu/Hr
* Do not include direct-vent gas appliances. Direct-vent draws combustion air from the outdoors and vents to the
outdoors.
4.
Compare the maximum Btu/Hr the space can support with the actual amount of Btu/Hr used.
__________________ Btu/Hr (maximum the space can support)
__________________ Btu/Hr (actual amount of Btu/Hr used)
Example:
63,300 Btu/Hr (maximum the space can support)
79,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the above example is a confined space because the actual Btu/Hr used is more than the maximum Btu/Hr the
space can support. You must provide additional fresh air. Your options are a follows:
A. Rework work sheet, adding the space of an adjoining room. If the extra space provides and unconfined space, remove
door to adjoining room or add ventilation grills between rooms, See
Ventilation Air from Inside Building
, page 9.
B. Vent room directly to the outdoors.
See ventilation Air
from Outdoors
, page 10.
C. Install a lower Btu/Hr logset, if lower Btu/Hr size makes
room unconfined.
If the actual Btu/Hr used is less than the maximum Btu/Hr the
space can support, the space is an unconfined space.
You will need no additional fresh air ventilation.
WARNING
If the area in which the firebox and gas log heater may
be operated is smaller than that defined as an unconfined
space, provide adequate combustion and ventilation air
by one of the methods described in the National Fuel
Gas Code, ANSI Z223.1, 1992, Section 5.3.
Содержание GLMVF38MVN
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